 Did you know rodents are frightened of some sounds in this video? We will look at how the ear works and how different animals can hear different sounds The visible part of the ear is called the pinner. It funnels sound into our ears The sound waves travel down the ear canal towards the eardrum The eardrum is a membrane at the end of the ear canal and is extremely sensitive Sound waves cause the eardrum to vibrate The cochlea is filled with fluid so as the eardrum vibrates the vibrations pass on to the fluid As the fluid vibrates this causes the small bones of the ear also to vibrate There are three small bones the hammer the anvil and the stirrup The last bone the stirrup is connected to another membrane which covers the entrance to the cochlea The vibrations pass through to the fluid inside the cochlea It is inside the cochlea that the sound waves are transformed from vibrations into electrical impulses When the fluid inside the cochlea vibrates this causes the microscopic hairs to also move This produces electrical signals which are then sent to the brain along the auditory nerve In the brain the electrical impulses are translated into sounds which we recognize and understand Most humans eardrums can vibrate at frequencies between 20 Hertz and 20,000 Hertz This is known as the human hearing range Anything outside of this range is either too low or too fast for our eardrum to cope with But not everyone has this exact range There are lots of reasons why people lose the ability to hear well Maybe damage to the eardrum Or the cochlea loses sensitivity with age Or prolonged exposure to loud noise Usually it's the higher frequencies that people can't hear as well as the age A normal middle-aged adult can often only hear up to about 14,000 Hertz Men's hearing often worsens more quickly than women's And so women can hear higher frequencies than men of the same age can do Any frequency that is below human range is known as infrasound And any frequency that is higher is known as ultrasound Animals can hear a different range of frequencies to humans Dogs can hear between 67 Hertz and 45,000 Hertz So humans can hear some sounds that are too lower frequency for dogs While dogs can hear some sounds that are too higher frequency for humans to hear Other animals hear other frequencies Elephants with their huge ears can hear lower frequencies than we can Differences in hearing range between animals can be used as a pest deterrent By playing sounds that are an unpleasant frequency to the animal but are undetected by humans This is used to deter pests such as rodents, spiders and insects So there you have how hearing works If you've ever heard the expression as quiet as a mouse You now know maybe that mice aren't quiet at all We just can't hear them